I have a 1999 Nordic Flame with 1999 Merc 502 MPI Mags. The starboard engine has been suddenly dropping out the last two outings. It seems that the engine quits when we hit a wave or any time the boat jolts onto the surface of the water. I am trying to make a list of connections to check and see if there is anything else that I haven't thought of or if any of these are in no possible way the problem. Here's my list so far...

Connections at battery
Connections at battery switch
Connections at starter
Connections at coil and distributer
Connections at ignition kill switch
Connections at ignition key switch
Connections at supply to circuit breaker panel board

Every time this has happened so far, the boat slams...my volts drop, and as the engine dies the oil pressure drops. I really want to get this fixed this week, any other suggestions on what the problem may be would be greatly appreciated.

Thanks

Check the connection to the cannon plug. Sometimes you need to bend the large prongs out alittle...sometimes it is just not pluged in all the way.

A few weeks back we hit a nasty wake and the entire harness from helm to motors fell from its mounting points. In turn it pulled out one of the wires leading to the kill switch lanyards.
I'd make sure all the harnesses are secured to the body and wont flop around in the rough stuff

I second this. It get overlooked often at a glance it may appear to be ok when in fact it is like stated above.

Check the hot lead at the alternator just to be sure as well.

Dave

The EFI loosing fuel pressure and killing the fuel supply caused from bad fuel flow when fuel pump sucking air from the tank when bouncing around in the waves?!

I don't think this is it...the tank is full and both engines draw from the same tank. It is also so instant that it almost has to be electrical. As soon as we hit the water, the engine dies like something just came unplugged. I am going to pull the boat out of storage tomorrow and start chasing everything down. I will start with the "cannon plug" and work my way from back to front through the boat. It's only gonna be 105 degrees here in Phoenix, should make for a fun day chasing wires

fire it up and wiggle the main plug. Odds are it will hiccup or quit.

Got it fixed this weekend, I want to thank everyone for their suggestions. Turns out it was the round "cannon" plug like several people suggested. I made sure that the plug was fully engaged and installed a stainless hose clamp. I took the boat out this weekend and it never stuttered once, and it was rough out there!

Thanks again guys, this site is a wealth of information.